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likuidkewl writes "Two super-earths, 5 and 7.5 times the size of our home, were found to be orbiting 61 Virginis a mere 28 light years away. 'These detections indicate that low-mass planets are quite common around nearby stars. The discovery of potentially habitable nearby worlds may be just a few years away,' said Steven Vogt, a professor of astronomy and astrophysics at UCSC. Among hundreds of our nearest stellar neighbors, 61 Vir stands out as being the most nearly similar to the Sun in terms of age, mass, and other essential properties."

A more massive Earth is no good, if I go there I will be hundreds of pounds (unless the planet's radii are more then 2.5 and 2.7 times greater then Earths). I want a smaller Earth to visit so my BMI calculation will no longer show me to be obese. Let me know when you find something with about 0.8 of Earths gravity.

I'll get excited when we find a planet about 93 million miles away from its star, the proper solar light properties for blue skin and near earth gravity. I've always had a thing for blue skinned alien girls.

We aren't as far off as you think. What's important is being able to constantly accelerate during the journey. Slow and steady acceleration wins the race. You're not going to do that with a chemical rocket, but with an on-board nuclear reactor and a few advancements in ion propulsion or vacuum propellers, we could make the trip. We could easily launch a probe to start making the journey in the next five years, if we allocated the budget to do so. Humans could make the trip as well, given the right accommodations--only a few years would be passing on-board. None of the technology to do this is very far-fetched at all, but we just aren't willing to spend the money.

If we stick with only 1.0G, then we wouldn't need artificial gravity for the people on board. We could maintain 1.0G acceleration on the way there, then spin the ship around (so the floor is pointing towards the destination) and maintain 1.0G deceleration for the second half of the journey.

The problem is, even if that means the people on board only experience 5-25 years, how much time will pass on Earth before we found out what this exploration team discovers there? (Remember, once they get there after however many years (hundreds? thousands?), they'd have to send their data by radio at light-speed, which would take yet another 28 years.) If we were to pony up the money to finance a mission like this, we, our children, our grandchildren, and our great-grandchildren would never find out the results, if any. We'd probably develop FTL in that time and have a colony already established on any viable planets in the 61 Virgo system before this team even arrived!

As far as I'm concerned, the only way any mission to another star system at low sub-light speeds makes any sense is if you're going to launch a "generation ship", a giant ship with an entire colony on board with everything needed to be self-sustaining indefinitely, so that this ship can travel from star system to star system, radioing back what it finds in each one and continuing until they find a place worth stopping at and establishing a permanent colony. But a ship like this would in itself be a major leap in technology, since we certainly don't have the capability to build such a massive space-based structure that can travel long distances through space, be self-supporting indefinitely, and able to handle any problems it might encounter (micrometeors?).

If we stick with only 1.0G, then we wouldn't need artificial gravity for the people on board. We could maintain 1.0G acceleration on the way there, then spin the ship around (so the floor is pointing towards the destination) and maintain 1.0G deceleration for the second half of the journey.

The problem is, even if that means the people on board only experience 5-25 years, how much time will pass on Earth before we found out what this exploration team discovers there? (Remember, once they get there after however many years (hundreds? thousands?), they'd have to send their data by radio at light-speed, which would take yet another 28 years.) If we were to pony up the money to finance a mission like this, we, our children, our grandchildren, and our great-grandchildren would never find out the results, if any. We'd probably develop FTL in that time and have a colony already established on any viable planets in the 61 Virgo system before this team even arrived!

1G = 7 years internal time, 30 years as time is measured on Earth. So you'd be getting messages back with 60 years.

0.01G = 100-odd years internal time, 107 years as time is measured on Earth. Messages back about 210 years after departure.

Note that 1G sustained isn't going to be practical for a very long time, but that 0.01G sustained (for 100+ years) is a maybe within the century.

Note that if we launched a 0.01G ship day after tomorrow, then sometime around 2185 we launched a 1G ship, the 1G ship would get there first.

On the other hand, I don't think a generation ship is entirely beyond the realms of possibility within the next 50 years. Yes, it would require some incredible engineering to get it done. But it wouldn't require as much new technology as one might think - the sheer size allows you to get away with things that aren't practical in a smaller ship. Like lakes, fields, forests, that sort of thing.

The problem here is that 1G sustained means your ship will be liveable by humans for those 7 years with no problem. 0.01G is not liveable at all; humans can't survive long-term in microgravity.

And of course it would be impossible to spin the ship, right?

Any ship big enough for a 100 year trip will be more than big enough to spin so that the rim of the ship experiences enough gravity to keep the crew healthy.

Not only that, 100 years is too long; no one will live that long (assuming you launch them when they're 20-25).

I take it you've never heard of the "generation ship" concept?

Humans can't live their entire lives (including their all-important formative years) in a small spacecraft with little social interaction.

And who ever suggested a small spacecraft? If I were designing it, it'd be 20 km long and 5-6 Km in diameter. With a crew of about 100,000.

A generation ship, however, could solve this problem (kids could very conceivably be raised on a giant ship with lakes and forests and a whole functioning mini-society), but as you said, this would require some incredible engineering. Lifting that much material into orbit really needs a space elevator, for starters.

So you DO know about generation ships! Great!

Hint: you don't build a generation ship from Earth. You start with an asteroid, and stock pretty much everything except the lifeforms aboard from other sources than Earth.

And this still doesn't address the gravity problem; those lakes and forests aren't going to work without artificial gravity.

Spin it. If it's six km in diameter, you have to spin it at 0.55 rpm to get 1G on the rim. And note that you have 360 km^2 worth of rim on the ship I described above. With a deck every 100 meters, we're talking a couple hundred thousand hectares at > 0.9G.

Alas, the likelihood of humanity building a generation ship is miniscule.

What passes for government here on Earth can't look far enough ahead. If we KNEW there was an alien species living there, and that they would be willing to give us the secret of FTL if only we sent someone there to collect, we'd still never get one built...

But the only real difficulty with doing so is the drive - the lifesystem, the physical structure, that sort of thing is almost trivial in comparison.

You wouldn't lift the whole mass of a generation ship from Earth, In fact the main mass would likely be a modified asteroid.
You need an asteroid of about the right composition and size/shape.Drill a hole down the center long ways and fill with mostly water and cap the end, then set spinning and focus sunlight on it with big mirrors. After a bit it gets hot and soft as the water inside boils providing the pressure to expand the now soft asteroid.
There is a lot of fine tuning involved, but you wind up with a miles long and wide cylinder that's hollow and spinning(living space and artificial grav), just ad atmosphere and equipment and colonist and propulsion.

If you built an generation ship that could last indefinitely, why bother landing on a planet at all? Everything you need is on the ship. Also, by the time you get to the planet, would your colonists even want to move to a planet? Considering they have spent generations on a ship, it may be that planetary living has become a very alien concept..